The present invention relates to the perfume industry. It relates more particularly to an alcohol-free concentrated perfuming composition in the form of a translucent oil-in-water emulsion. This perfuming composition can be used in particular in the form of a perfumed emulsion capable of being atomized onto the skin or hair, on to quite different types of surfaces, or simply into the ambient air.
Oil-in-water emulsions are well known in the cosmetics industry and in dermatology, in particular for the preparation of cosmetic products such as creams, lotions, tonics or serums. Emulsions such as this are for example described in European patent EP 728 460, which relates more particularly to transparent nanoemulsions based on non-ionic amphiphilic liquid lipids and their use in cosmetics and dermopharmacy. These emulsions always contain a small proportion of a low-molecular-weight alcohol.
The problems associated with the formulation of emulsions in the cosmetics industry are not the same as those encountered in perfumery. The objective of hair-care and skin-care products and of products for cleaning the hair and skin is to optimize the penetration of active substances into the superficial layers of the skin. Moreover, these cosmetic emulsions are of a highly specific composition and are characterized in particular by the fact that their oil phase comprises a large variety of active substances such as natural or synthetic oils, hydrocarbons, halogenated hydrocarbons, mineral acid esters or silicones, differing according to the desired application. In contrast with a cosmetic composition, a perfuming composition is a perfume carrier the primary function of which is to impart a scent to a product. In the form of an emulsion, its oil phase is made up essentially of perfuming ingredients. It will be easily understood that the problems to be resolved when formulating emulsions, such as in particular optimization of the parameters capable of influencing the stability of the product, are posed differently in different industries. The solutions to these problems in fact depend on the desired objective for the product and more precisely on the composition of the continuous and dispersed phases, and therefore cannot be applied to perfumery simply on the analogy of fields such as cosmetics or dermatology. The problems of stability specific to the emulsification of a perfume are moreover well known in the perfume industry (see the magazine Cosmetics and Toiletries(copyright), vol. 109, pages 71-75, 1994) and relate to the nature of the emulsified ingredients, i.e., the perfuming ingredients.
Furthermore, apart from having chemical stability, an emulsion must also meet certain requirements regarding physical stability. For example, one of the phenomena typically associated with the physical instability of an emulsion is the ascending and descending movement of the dispersed droplets relative to the continuous phase. These phenomena are called creaming or sedimentation, respectively.
Microemulsions are dispersed systems which provide a solution to the problems of destabilization which, in the case of a conventional emulsion, lead to phase separation. These systems are widely described in the prior art, for example in patent applications or patents such as EP 516 508; EP 572 080; U.S. Pat. Nos. 5,320,863; 5,585,343 or FR 2,703,926. These documents all describe dispersions of oil and water that are homogeneous, transparent and stable, with these properties originating from the large quantities of added surfactants and co-surfactants.
Microemulsions and emulsions constitute two disperse systems of very distinct types. Whereas emulsions are unstable systems, microemulsions are stable and form spontaneously when oil, water, surfactants and co-surfactants are mixed together. The thermodynamic stability of a microemulsion is revealed in particular by the fact that, in contrast with an emulsion, the mean droplet size in the system does not vary over time. The two disperse systems also differ in respect of their optical properties, microemulsions having a mean droplet size much less than the wavelength of light and a relatively narrow droplet-size distribution. This type of formulation thus diffuses light only slightly and is consequently transparent, while emulsions have a droplet size comparable to or greater than the wavelength of visible light and a broader droplet-size distribution so they diffuse light, thus yielding an optical effect ranging from milky to translucent.
In any case, it is very clear to the person skilled in the art who is familiar with the different types of disperse systems that emulsions and microemulsions constitute two very different systems.
Now, the aim of the present invention is to create in particular compositions which do not incorporate large quantities of surfactants relative to the quantity of perfuming ingredients, the presence of surfactants considerably limiting the proportion of perfume that can be added to the mixture. This is why a disperse system of the microemulsion type is unsuitable for the present invention, which therefore relates to a product in the form of an oil-in-water emulsion which, its nature notwithstanding, nevertheless possesses quite surprising physical stability.
Another problem specific to the perfume industry is that of the typical presence of alcohol. Ethanol is very widely used as a solvent in the preparation of perfumed compositions such as perfumes, eaux de toilette, eaux de Cologne, or deodorising compositions for example. Ethanol enables good solubilization of the perfuming ingredients available to the perfumer. It thus constitutes the principle vector used in perfumed body-care products (perfumes, eaux de toilette, deodorants, after-shaves etc.) and, as it is virtually odorless, it is a very good solvent which evaporates rapidly thus imparting a cooling sensation. For these reasons, the majority of commercially available perfuming compositions contain ethanol, generally in a proportion of 50 to 95% by volume.
However, ethanol is significantly volatile, and it is sometimes desirable to obtain perfuming compositions with a very low, or even a zero alcohol content.
On the international market, there currently is a trend towards alcohol-free perfumes, with this trend arising both from the regulation of VOCs (volatile organic compounds) as well as from the preference of the consumer for alcohol-free products intended for sensitive skins and which can be used safely in sunlight.
Japanese patent application JP 96225429 discloses perfuming compositions which, despite being designated xe2x80x9calcohol-freexe2x80x9d, generally always contain a small proportion of alcohol. This application describes perfuming compositions which are either liquid or in the form of a gel, and comprise in particular water-soluble polymers such as gums. These type polymers, which are well-known in relation to emulsions, are used as a stabilizing agent. However, it is also known that the use of these polymers has the disadvantage of rendering emulsions sticky to the touch. These constituents furthermore have the effect of considerably increasing the viscosity of the emulsions in which they are contained. The cited Japanese patent application also states that the products obtained are sometimes viscous or even in the form of gels.
The present invention proposes to solve the problem of obtaining a perfuming product in the form of a translucent alcohol-free emulsion which is atomizable and capable of containing a large proportion of perfume, is of a pleasing appearance and pleasant to the touch, as well as having good long-term stability. No document of the prior art describes emulsions such as this, meaning that it has not yet been possible to solve the problem posed.
The present invention provides a solution to the various problems mentioned, by means of an alcohol-free perfuming composition in the form of an atomizable, translucent oil-in-water emulsion containing at least one perfuming ingredient, a surfactant system having a hydrophilic-lipophilic balance (HLB) greater than or equal to 10, and water. Perfuming composition is used herein to mean a composition the primary function of which is to modify the odor of a product or to impart an odor to a product or a person. The composition of the invention has been optimized so as to be able to contain large quantities of perfume, that is, between 0.1 and 18% by weight relative to the total weight of the emulsion. The emulsion is also very stable, as shown by the variation in the mean droplet size in the first month following its formulation, wherein this variation is within the range of 0.1 to 30 nm at a temperature of 45xc2x0 C.
The emulsion forming the subject of the present invention has numerous advantages for its intended use. Firstly, as mentioned above, this compositionxe2x80x94which is intended in particular to be atomized onto the skin or hair, onto quite different types of surfaces to be perfumed, or simply into the ambient airxe2x80x94contains a particularly high concentration of perfuming ingredients.
Secondly, the mean droplet size is such that the emulsion advantageously satisfies the desired stability criteria (i.e., the absence of the creaming or sedimentation effects) without requiring the presence of stabilizing agents such as water-soluble polymers, as is the case in the prior art. The absence of these constituents has the advantage of providing a substance of low viscosity which is atomizable and non-sticky to the touch. The viscosity of the compositions according to the invention is preferably below 1 Pa.s.
Moreover, the mean droplet size of the emulsion exerts an optical effect on the end product, the translucent appearance of which with its bluish shimmer is greatly liked by the consumer and is especially well adapted to a use for perfume-derived products, such as atomizable perfume emulsions. Generally, the optical properties of the compositions of the invention are characterized by a transmission varying between 10 and 90% when measured at a wavelength of 600 nm at 25xc2x0 C. in a cell with a thickness of 1 cm.
Other advantages will appear in the course of the detailed description of the invention and via the examples cited for illustration purposes.